The primary aim of this R21 application in response to NIDA's ANSWHR Initiative (PAS-07-381) is to address gaps in literature focused on HIV risk and disparities among females. In the United States as rates have increased among females, the rate of HIV/AIDS diagnoses for African American females approaches 25 times the rate for white females. Despite the broad base of findings documenting health disparities in HIV, extant studies cannot explain why African Americans continue to be disproportionately affected. Currently, there is a hidden HIV epidemic among young adult African American females with no history of substance abuse. These women are at increased risk for contracting HIV by virtue of their social networks. The proposed study requests two years of support for a cross sectional epidemiologic examination of racial/ethnic differences in sexual partnerships among 220 females (110 Black and 110 White) residing in low socioeconomic status (SES) neighborhoods. Guided by ecosocial theory, we seek to explain why these differences exist across race/ethnicity. We will consider the extent to which neighborhood social and economic factors (e.g., drug markets) interact with race/ethnicity to produce different levels of HIV risk. We will expand drug abuse and HIV prevention research by, in addition to considering individual differences, examining the influences of neighborhood drug markets on the sexual behaviors, sexual partnerships and rates of a sexually transmitted disease among young adult females residing in disadvantaged neighborhoods. Finally, the proposed study will move beyond descriptive social epidemiology and into identifying neurocognitive processes that mediate/moderate relationships between neighborhood factors and individual behavior. As, a small yet growing base of research suggests, to the extent that individuals are able to make decisions, solve problems and control impulses, neurocognitive functions may serve as protective factors or pathways through which external social factors influence individual behavior. Identifying social factors that influence partner selection and individual level factors that may serve to reduce the adverse effects of living in disadvantage neighborhoods will inform HIV prevention interventions for African American and underserved women. If successful, the proposed research project: (1) should provide insight into why African American females have higher rates of HIV than their white counterparts;(2) highlight the importance of considering the contextual influences of drugs, that is the influence of drug markets on social structures and sexual norms and behaviors;and (3) identify modifiable individual level factors linking neighborhood social and economic factors to individual HIV risk behaviors. PUBLIC HEALTH RELEVANCE: Currently, there is a hidden HIV epidemic among young adult African American females with no history of substance abuse. These women are at increased risk for contracting HIV by virtue of their social/sexual networks. If successful, the proposed research project: (1) should provide insight into why African American females have higher rates of HIV than their white counterparts;(2) highlight the importance of considering the contextual influences of drugs, that is how drug markets change social structures and altered sexual norms and behaviors of entire communities;and (3) increase understanding of the processes through which neighborhood factors influence HIV risk.